[Amazon] Silicon Power 2TB Rugged 2.5" USB3 External HDD US $105.99 (~AUD $126.09 Delivered)
Well reviewed. Approx $200 from Aussie sellers. http://camelcamelcamel.com/Silicon-Power-Military-Shockproof...
Silicon Power 2TB Rugged Armor A30 Military Shockproof Standard 2.5-Inch USB 3.0 External Portable Hard Drive - Black (SP020TBPHDA30S3K)
Edit: also, 1TB A30 for ~A$84 delivered http://www.amazon.com/Silicon-Power-Military-Shockproof-Stan... thanks to Possumbly
Edit 2: also, the A80 series is a water resistant and metal-enclosure option for a few more bucks (AU$142 delivered for 2TB version) http://www.amazon.com/dp/B00KF4E83G/ref=twister_B00KW5Z2A6